The Use of Portable Raman Spectroscopy to Identify Conservation Treatments Applied to Heritage Stone

Non-destructive in situ analysis of materials is highly desirable in cultural heritage studies, for it precludes the need for intensive sampling. The present study focused on the usability of Raman spectrometers, which can provide such analysis, in the identification of conservation treatments applied to stone materials forming part of the architectural heritage. Two products commonly used to conserve stone monuments, an ethylmethacrylate co-polymer and an ethyl orthosilicate, were analysed with a Raman spectrometer, both as supplied and after application to limestone. The main conclusion drawn was that portable Raman analysers can detect the presence, and in some cases identify the nature, of products on stone substrates. The latter is not always possible due to product-stone substrate interaction. The study clearly showed that a product and substrate database is needed for portable Raman spectroscopy to be usable in the analysis of conservation products, both before and after application to stone substrates.